With China continually rattling the saber in the East China Sea, the airport on Shimoji Island, Okinawa Prefecture, is quietly receiving growing attention because of its military potential.

Shimoji Island is adjacent to Miyako Island, which is 200 kilometers southeast of the Senkaku Islands. Between Miyako Island and the main island of Okinawa lies the 260-km-wide Miyako Channel, which serves as a major choke point for China’s naval power projection toward the Western Pacific.

Shimoji airport is the best civil airport in the region, equipped with a 3,000- meter-long, 60-meter-wide runway, a 30-meter-wide taxiway and other necessary facilities and installations. It could accommodate the needs of almost any military aircraft including large transport and other support planes.

At present, the airport is used exclusively for jet aircraft pilot training, including jumbo jets’ touch-and-go landings. The islet is inhabited solely by a small number of operating staffers, who could be easily moved out.

The underutilized Shimoji airport contrasts sharply with the overcrowded dual-use Naha International Airport on Okinawa Island, which, with a 3,000-meter-long but only 45-meter-wide runway, accommodates Air, Maritime, and Ground Self-Defense Force aircraft and Japan Coast Guard airplanes, in addition to a great number of regular commercial flights. Naha airport’s civil air traffic control authority sometimes gives priority to safety considerations at the sacrifice of military needs, especially scrambling.

Without requiring significant additional defense spending, a sine quo non during fiscal austerity, Japanese air power would be more survivable against possible Chinese salvos of ballistic and cruise missiles if Shimoji airport were transformed into a military or at least a dual-use facility and if SDF aircraft — especially the F-15 air superiority fighters assigned to the ASDF Southwestern Composite Air Division’s Second Squadron set to be deployed at Naha airport — were diverted from Naha airport.

Shimoji airport would also have sufficient capacity for both parking and logistics and would be able to receive reinforcements from mainland Japan and the continental United States in case of a major regional contingency.

The above idea based on military rationality has long been a nonstarter due to the memorandum prohibiting military use of Shimoji airport, which was concluded in 1971 between the Japanese Government and the Government of Ryukyu Islands under postwar U.S. military administration.

Behind it is the strong anti-military and pacifist political culture of the Okinawans, who suffered greatly from the disastrous Battle of Okinawa — which was fought mainly on Okinawa Island — and have been forced to accept the heavy presence of U.S. military bases.

The post-reversion Okinawa prefectural government owns and administers Shimoji airport. Its operating cost has been covered by revenue from use fees for training at the airport by civil aviation companies, primarily the Japan Airlines and All Nippon Airways.

Shimoji airport, however, is now a white elephant for the Okinawa prefectural government because its revenue has drastically dwindled due to the advent of high-tech simulators for virtual flight training, which has replaced expensive, risky touch-and-go or single-engine landing, among other things.

With fuel prices soaring due to a cheap yen, JAL has stopped using the airport for training, while ANA is under increasing financial pressure to exit. In 2014, the Okinawa prefectural government, for the first time, was forced to fill in a revenue-outlay gap with funds from its general account expenditures.

In the meantime, local residents are not ready to give up Miyako-Jima (aka Miyako) airport located at the very center of Miyako Island. It is equipped with a 2,000-meter-long runway but no taxiway. This poses an obstacle to transportation of a large number of passengers and hinders full development of local tourism. Currently a 3,450-meter bridge is being constructed to connect Shimoji airport with Miyako Island. But the bridge is susceptible to suspension of (automobile) traffic during windstorms, particularly in typhoon season. Neither airport can fully fill local needs.

Entrapped with bottlenecks in infrastructure for tourism and facing rapid graying of the population and a steady emigration of younger workers to the main island of Okinawa, the predominantly agrarian local economy is experiencing a gradual decline.

Furthermore, the Miyako city government depends on subsidies from the central government for some 80 percent of its annual budget. Thus there is little room for the city government to take industrial development initiatives.

Inviting an SDF air base to Shimoji airport is the only viable economic option. But this idea is hard to sell in the context of predominantly pacifist local political discourse, particularly in the Okinawa Prefectural Assembly.

Nor will the prefectural assembly keep financing the operating cost of Shimoji airport by using general account expenditures, which would breach the principle of a self-supporting accounting system for the airport. Indecision will lead, sooner rather than later, to the shutdown and abolition of the airport.

But here is a legal breakthrough to untie the Gordian knot. The abolition of the airport would reduce its land, facilities and installation to mere real estate property, which would annul the memorandum prohibiting military use of the airport. Once the airport is abolished, the central government would be able to purchase its land, facilities and installations as real estate property.

The time is ripe to settle the Shimoji airport issue for future active use. The central government should not directly intervene in the dynamics of local politics, but it should quietly prepare a concrete policy package that would lead to use of the airport for either an exclusively military or a dual-use purpose.

Masahiro Matsumura is a professor of international politics at St. Andrew’s University in Izumi, Osaka.

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